This invention relates to textile machinery, such as tufting machines and the like, and is particularly directed to yarn feed roller pattern attachments therefor.
Wide use is being made of pattern attachments for producing variations in pile height in pile fabric such as carpeting. Representative of such pattern attachments are those disclosed in the following U.S. Pats: Card, No. 2,862,465; Nix, No. 2,875,714; Card, No. 2,966,866; MacCaffray, No. 3,001,388; Card, No. 3,075,482; Hammel, No. 3,103,187; Beasley, No. 3,134,529; Card, No. 3,207,105; Card, No. 3,224,395; Erwin, et.al., No. 3,272,163; Singleton, No. 3,489,326; Short, No. 3,605,660; Short, No. 3,752,094; and Hammel, No. 3,847,098. These attachments include a plurality of yarn feed rollers which feed yarn to the needles of the tufting machine. Each of the feed rollers is selectively driven at one of a plurality of different speeds independently of the other feed rolls by means of clutches controlled by a pattern control. The amount of yarn supplied to the needles of a tufting machine or the like is determined by the rotational speed of the feed rollers on which the yarn strand is wound, so that with a fixed needle stroke the amount of yarn supplied to the needle determines the pile height of the pile fabric produced. To create patterned pile effects the amount of yarn fed to the individual needles may be varied by driving the feed rolls selectively at different speeds.
With the exception of the disclosures in the two aforementioned Short patents, each feed roller of the prior art attachments feeds a plurality of yarn ends to selected needles. Since each needle receiving yarn from a given roller must necessarily always produce a pile loop of the same height as that of the other needles receiving yarn from that roller, the number of pattern repeats across the width of the work products is limited. For example, a tufting machine for producing carpeting may have 1,200 needles spaced transversely across the machine. If a pattern attachment having 120 feed roller sets controls the feeding of the yarn ends, there would be ten pattern repeats across the face of the carpet and each roller set would control ten yarn ends. If eight repeats are desired, then 150 roller sets would be required if the same carpet were produced. If less rolls were available, e.g. 120, then eight repeats would be obtained by sewing a smaller width or by increasing the gauge so that only 960 needles would be used.
The limitations on the number of rollers restricts the carpet designer to designs which repeat frequently across the width of the carpet. It would therefore be desirable to have a pattern attachment capable of individual yarn end control or at least approaching such control. Due to space limitations the prior art designs have not generally been adoptable to the large number of rollers required for individual yarn control. The Short patents are attempts toward this end.
Each yarn feed roller type of pattern attachment comprises a large number of clutches. As pointed out in the aforesaid Hammel U.S. Pat. No. 3,847,098, the clutch members generally wear out or become defective before the other parts and must be replaced for service periodically. Unless the pattern attachment is designed with service in mind, the amount of "down-time" would be excessive with the additional costs reflected in the price of the carpeting. With an attachment having the number of rollers approaching individual yarn end control, the amount of down-time would be staggering if servicing would require more than a minimal amount of down-time. The result of this would be to make such multi-roller controls unfeasible for economical carpet production.